Not Applicable
Not Applicable
This invention is a machine for controlling the motion of a spherical capsule containing one or more occupants. Possible applications include flight simulation, virtual reality, and 3D game playing.
U.S. Pat. No. 3,135,057 to Nelson et al. (1964) describes a spherical capsule floating on a precision fluid bearing. Capsule motion is generated by the use of electric motors attached to three large circular bearing assemblies located in the interior of the capsule. Activating a motor causes the capsule to rotate in the direction opposite of the motor""s movement.
The Nelson et al. design has some drawbacks. The stated primary purpose of the Nelson et al. design is the simulation of instability during space flight. Continuous rotation of the capsule around an axis cannot be sustained. This is unfortunate because continuous rotation would probably best simulate the actual motion of a spacecraft spinning out of control.
Locating large power supplies and drive motors in the interior of the capsule undoubtedly adds heat and noise to a very confined space. The use of a precision fluid bearing to support the capsule means the dimensional tolerances of the capsule""s exterior surface are critical. Finally, the three large custom bearing assemblies, each a couple meters in diameter, would most certainly be very expensive to manufacture.
U.S. Pat. No. 5,060,932 to Yamaguchi (1991) is a design that uses two concentric gimbal rings to support a spherical capsule. An individual motor controls the rotation of each ring, and ultimately the innermost capsule. An inherent problem with nested gimbal mechanisms is the accumulation of mass as each ring is layered around the central capsule.
Every individual motor in the Yamaguchi design, by itself, must be able to rotate the capsule. This mandates the use of large, powerful motors. Large motors add substantial and undesirable weight to the ring assemblies. Smaller motors might be adapted by gearing down the output. Unfortunately, geared down small motors would almost certainly result in sluggish rotational acceleration and deceleration.
U.S. Pat. No. 6,017,276 to Elson et al. (2000) describes a spherical capsule that is rotated by means of external drive components. The physics of a spherical capsule using external drive results in a machine that is more viable than nested gimbal designs. Keeping the drive mechanism separate from the capsule frees the capsule from the weight and undesirable flywheel effects of those components.
The Elson et al. design uses three rotary actuators whose axes are set orthogonal to each other. The design also specifies the use of rotary actuators that allow slippage to occur in the transverse direction. This means the actuators must simultaneously provide secure traction only in their intended driving direction, yet freely permit slippage at right angles. This is a significant task when accelerating and decelerating a capsule weighting possibly hundreds of kilograms. Rotary actuators mounted with their axes at orthogonal angles will, to a certain extent, always be fighting each other whenever the capsule is in motion. This is especially true when the movement of the capsule""s surface is substantially oblique to the axes of the rotary actuators.
The Elson et al. design is an improvement over earlier designs, and accomplishes much with the separation of the capsule from the drive components. The development of a practical rotary actuator that could successfully provide transverse slippage might prove possible. However, significant advances in the design, performance, and practicality of machines in this field are realized by the Agile Capsule Motion Machine.
Objects and Advantages
Several objects and advantages of my invention are:
(a) to provide a motion machine that is nimble and highly responsive to occupant control;
(b) to provide a motion machine with unlimited freedom of rotation about three axes;
(c) to provide a motion machine that can be networked with similar machines;
(d) to provide a motion machine that maximizes the use of standard, off the shelf components;
(e) to provide a motion machine that functions reliably, and is easy to maintain;
(f) to provide a motion machine that is energy efficient.
My invention best shown in FIG. 1A is comprised of a lightweight spherical capsule 40 with locations for one or more occupants. The capsule floats on a cushion of compressed air. Six stepper motors 48 are positioned around the horizontal circumference of the capsule. Driving simple rubber wheels 46, the stepper motors provide any combination of pitch and roll motion to the capsule with both precision and efficiency. The drive wheels and stepper motors themselves are mounted on a rotatable drive assembly 49, which provides precision yaw control for the capsule.
The activation of the stepper motors while they are in rotation about the capsule provides freedom for unlimited capsule rotation in any direction. This is accomplished without the accumulation of rotational mass and oversized motors as seen in nested gimbal designs. The circular array of simple drive wheels provides excellent traction and control of the capsule at all times. The problems of how to construct a practical transverse slippage rotary actuator are avoided.